This contribution describes John Calvin's understanding of what it means to be a Christian. When Calvin 'converted' to the Reformation in the early 1530s, the term 'Protestant' did not exist. There was no systematic body of doctrine or a confession you could put your signature under. So Calvin became a 'lover of Christ'. The unity with Christ was a central part of his theology but also his personal spirituality. Calvin also understood his own conversion as a 'conversio subita ad docelitam', a conversion to a 'teachable frame of mind'. Calvin's love for Christ, his love for the Word of God and a teachable frame of mind not only defined his theology, but also his piety and spirituality